The ancient reptile Thrinaxodon, an ancestor of mammals, had skull features suggesting that it had sensory whiskers. If Thrinaxodon had whiskers, it clearly also had hair on other parts of its body, which would have served as insulation that regulated body temperature. Therefore, Thrinaxodon was probably warm-blooded, for such insulation would be of little use to a cold-blooded animal.
Summarize Argument
The author concludes that Thrinaxodon was probably warm-blooded. As support, the author says that its skull suggests that it had whiskers. The author then provides the following conditional premise: If Thrinaxodon had whiskers→ Thrinaxodon had hair elsewhere on its body. The author claims that this hair elsewhere on its body would have regulated its body temperature. The evidence cited by the author affirms the sufficient condition (that Thrinaxodon probably had whiskers), so we can say that it probably had hair elsewhere. Since cold-blooded animals would have little use for insulation, the author concludes that Thrinaxodon was probably warm blooded.
Identify Argument Part
The statement in the question stem provides support for the claim that Thrinaxodon was warm-blooded, because a cold-blooded animal would have little use for such insulation.
A
It is a premise offered in support of the conclusion that insulation regulating body temperature would be of little use to a cold-blooded animal.
The conclusion of the argument is not that insulation regulating body temperature would be of little use to a cold-blooded animal; rather, the conclusion is that Thrinaxodon was probably warm-blooded.
B
It is a premise offered in support of the main conclusion drawn in the argument.
The statement in the question stem is a premise that supports the conclusion that Thrinaxodon was probably warm-blooded, since cold-blooded animals would have little such for such insulation.
C
It is a conclusion for which the claim that Thrinaxodon had skull features suggesting that it had sensory whiskers is offered as support.
The claim in the question stem is not a conclusion, it is a premise.
D
It is a statement of a hypothesis that the argument attempts to show is false.
The claim in the question stem is used to support the argument’s conclusion; the argument is not trying to show that this information is false.
E
It is offered as an explanation of the phenomenon described by the argument’s main conclusion, but it is not itself used to provide support for that conclusion.
The statement in the question stem does provide support for the conclusion, so (E) is descriptively inaccurate.
Economist: Currently, many countries rely primarily on taxing income to fund government expenditures. But taxing income does nothing to promote savings and investment. Taxing consumption, on the other hand, would encourage savings. The most important challenge facing these countries is improving their economies, and the only way to accomplish this is to increase their savings rates. Hence, _______.
Summary
Many countries primarily rely on taxing income to support government spending. Taxing income does not promote savings and investment. In contrast, taxing consumption would encourage saving. In these countries, the biggest challenge is improving their economies. The only way to accomplish this is to increase savings rates.
Strongly Supported Conclusions
Hence, many countries should primarily tax consumption as opposed to income.
A
most governments should stop taxing savings and investment
This answer is unsupported. To say that most governments should take action is too strong. The stimulus is limited to “many” countries, not most countries.
B
the economies of countries will rapidly improve if their governments adopt tax policies that encourage savings and investment
This answer is unsupported. We don’t know from the stimulus whether these countries’ economies would improve rapidly. It could be the case that they improve slowly, or gradually.
C
in most countries taxes on consumption alone could raise adequate revenues to fund government expenditures
This answer is unsupported. To say that most countries could achieve this is too strong. The stimulus is limited to “many” countries, not most countries.
D
the tax laws of many countries should be revised to focus on taxing consumption rather than income
This answer is strongly supported. We know from the stimulus that taxing consumption encourages savings. Therefore, this would be a better strategy for improving savings rates than taxing income.
E
it is detrimental to the economic improvement of any country to continue to tax income
This answer is unsupported. To say that this is detrimental to any country is too strong. The stimulus is limited to “many” countries, not any country.
Summarize Argument: Counter-Position
Some citizens argue that, because users of a proposed trail would likely litter an area, that the development of the trail should not proceed.
The author asserts that because most trail users will be dedicated hikers who care about the environment, the particular complaint about hikers’ likelihood to litter is groundless. Thus, the author concludes, trail development should proceed.
Identify and Describe Flaw
The author assumes that showing the citizens’ support for their conclusion is wrong proves that the citizens’ conclusion is wrong. In other words, the author overlooks the possibility that even if the particular objection concerning littering is groundless, we still should not proceed with development of the trail.
A
bases its conclusion mainly on a claim that an opposing argument is weak
The author points out the citizens’ argument is weak — the citizens’ premise concerning likelihood of littering is groundless. But this doesn’t prove that trail development should proceed. The citizens’ conclusion can still be right, even if the argument in support of it is weak.
B
illicitly infers that because each member of a set has a certain property that set itself has the property
The author doesn’t cite to a premise stating that each member of a set (trail users) has great concern for the environment. The premise says “most” trail users will have great concern; this isn’t a claim about “each” trail user.
C
illicitly assumes as one of its premises the contention it purports to show
(C) describes circular reasoning. None of the author’s conclusions are assumed in the premise. The premise is that most trail users will have great concern for the environment; this idea is not restated in any of the author’s conclusions.
D
illicitly infers that an attribute of a few users of the proposed trail will characterize a majority of users of the trail
The author’s premise asserts that “most” trail users will have great concern for the environment. This is simply a fact that we accept as true, because it is a premise. The author did not try to infer this premise from some other claim about a few trail users.
E
attacks the citizens in the group rather than their objection to developing the trail
The author does not attack the citizens. The author attacks the argument the citizens gave in support of their conclusion.
Summarize Argument
The author concludes administrators, corporations, and agencies were incorrect when they predicted an imminent, catastrophic shortage of scientists and engineers. Why? Because the salaries of scientists and engineers haven’t increased much, and their unemployment rates aren’t especially low.
Notable Assumptions
The author assumes any catastrophic shortage of scientists and engineers would have caused upward salary pressure or low unemployment for them. In addition, he assumes the administrators, corporations, and agencies predicted the imminent shortage would be at the present time, not in the past or future.
A
The proportion of all research in science and engineering being carried out by corporations is larger than it was five years ago.
This doesn’t mean there are plenty of scientists and engineers. It’s possible all sorts of institutions would be doing more research if there were more scientists and engineers available.
B
Most students choose fields of study that offer some prospect of financial success.
This doesn’t imply the number of scientists or engineers meets the demand for them—nor even that lots of students choose to study science and engineering. The author doesn’t say science and engineering offer a prospect of financial success that other fields don’t.
C
The number of students in university programs in science and engineering has increased significantly in the last five years.
This makes the author’s key claim—that there’s no shortage of scientists and engineers—more likely. It suggests circumstances have changed to allow for more scientists and engineers to enter the workforce since the predictions were made.
D
Certain specializations in science and engineering have an oversupply of labor and others have shortages.
If anything, this weakens the argument. It implies there are shortages of at least some types of scientists and engineers, making the author’s key claim—that there’s no widespread shortage—less likely.
E
The knowledge and skills acquired during university programs in science and engineering need to be kept current through periodic retraining and professional experience.
This requirement could help explain a shortage—it doesn’t make a shortage less likely. If anything, this extra requirement for scientists and engineers to remain proficient makes a shortage slightly more probable.
Summarize Argument: Phenomenon-Hypothesis
The author concludes that people with [greater tendency to laugh] are helped more in their recovery from illness than are patients with [lower tendency to laugh] even when the [greater tendency to laugh] people laugh only a little and the [lower tendency to laugh] people laugh more. This is based on a study in which [greater tendency to laugh] people recovered more than [lower tendency to laugh] people after watching a funny videos. In addition, there’s evidence that laughter can help recovery from illness.
Identify and Describe Flaw
The author overlooks the possibility that the [greater tendency to laugh] people actually laughed more at the funny videos. That might be why they recovered more. We’re given no reason to think they laughed only a little.
A
overlooks the possibility that the patients whose tendency to laugh was greater to begin with laughed more at the comic videos than did the other patients
This possibility, if true, provides another explanation for why the [greater tendency to laugh] people recovered more. It could be that they laughed more, and not due to the underlying inherent greater tendency, divorced from the actual amount of laughter.
B
fails to address adequately the possibility that the patients whose tendency to laugh was greatest to begin with already had stronger immune systems than the other patients
The possibility in (B) wouldn’t affect the argument, because the study involved a comparison of which kind of patient recovered more. It was about who experienced a greater increase in immune system strength, not about how one group’s absolute strength compared to the other’s.
C
presumes, without providing justification, that hospital patients have immune systems representative of those of the entire population
The author didn’t generalize from hospital patients to the entire population. The conclusion is about hospital patients, not other people.
D
takes for granted that the gains in immune system strength did not themselves influence the patients’ tendency to laugh
The author doesn’t assume this, because the premise is about people whose tendency to laugh was “greater to begin with.” So they started with a greater tendency, then watched the funny videos.
E
presumes, without providing justification, that the patients whose tendency to laugh was greatest to begin with recovered from their illnesses more rapidly than the other patients
The speed with which patients recovered is irrelevant, because both the study and conclusion concern a comparison regarding who recovered “more”. Someone can recover a small amount quickly or slowly, or a large amount quickly or slowly. Rapidity is different from magnitude.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that male guppies change their courting behavior based on feedback from female guppies. Why? Because in a study, male guppies showed their side with more orange to females, and females were attracted to males showing the most orange.
Notable Assumptions
The author assumes male guppies usually showed their more-orange sides to females in response to feedback from those females, and not for any other reason. This means assuming male guppies observed that females preferred mates with more orange and changed their behavior in response. Therefore the author assumes that before making those observations, male guppies were no more likely to show females their more-orange side.
A
When a model of a female guppy was substituted for the female guppy, male guppies still courted, but were not more likely to show their side with more orange.
This rules out an alternative hypothesis: that male guppies always show females their side with the most orange, regardless of the females’ behavior.
B
In many other species females show a preference for symmetry of coloring rather than quantity of coloring.
This is irrelevant. It doesn’t say guppies are one such species—and even if they were, it wouldn’t imply that male guppies learn to show their side with the most orange in response to the females’ behavior.
C
No studies have been done on whether male guppies with more orange coloring father more offspring than those with less orange coloring.
This is irrelevant. It’s an opportunity for further research that could support the author’s hypothesis. The fact it hasn’t been done doesn’t make that hypothesis any more likely.
D
Female guppies have little if any orange coloring on their sides.
This is irrelevant. There’s no indication male or female guppies change their behavior based on the appearance of female guppies.
E
The male and female guppies were kept in separate tanks so they could see each other but not otherwise directly interact.
If anything, this weakens the argument. It raises the possibility that the male guppies were not actually courting the female guppies or that females were not responding to that courting. If true, either of these scenarios would call the author’s hypothesis into question.
Summarize Argument: Causal Explanation
The politician concludes that it would be dangerous to follow the argument for unilateral arms reduction, since nuclearized countries on the verge of civil war can’t be relied on to reduce their nuclear arsenals in turn.
Identify Conclusion
The conclusion makes a case against the politician’s country acting on unilateral arms reduction: “Our acting on the basis of this argument would be dangerous.”
A
Countries that are on the verge of civil wars are unlikely to agree to reduce either their nuclear arms or their conventional weapons.
This is a premise that supports the politician’s conclusion. Since countries on the verge of civil war are unlikely to reduce their arsenals, unilateral arms reduction wouldn’t achieve broad disarmament.
B
Unilateral nuclear arms reduction by the politician’s country would encourage all countries to reduce their nuclear arsenals.
This is a component of the reasoning that the politician argues against embracing. The politician believes there are risks that this line of reasoning doesn’t factor in.
C
Many countries cannot be relied upon to disclose the extent of their nuclear capability.
This doesn’t appear in the politician’s argument. The politician says many countries can’t be relied upon to conform to international military policy, but we don’t know anything about specifically disclosing their nuclear capability.
D
It is unlikely that an international agreement on nuclear disarmament will ever be achieved.
This doesn’t appear in the politician’s argument. The politician simply states that unilateral disarmament wouldn’t be wise at the present time.
E
It is risky for the politician’s country to unilaterally reduce nuclear arms in hopes of achieving an international agreement on arms reduction.
Since many countries wouldn’t follow international military policy, unilateral arms reduction wouldn’t achieve its aims. It’s risky to give up weapons when other countries aren’t doing the same.
Summarize Argument
The author concludes that after any accident that involves a fall or bump on the head, you should get Lakeside Clinic’s complete course of treatment for whiplash. This is based on the fact that whiplash is caused by a sudden, sharp movement of the neck, and many things can result in a sudden, sharp movement of the neck, including a fall or a bump on the head.
Notable Assumptions
The author assumes that every fall or bump on the head involves a sudden, sharp movement of the neck. The author also assumes that there aren’t significant harmful effects from a complete course of treatment for whiplash that might weigh against going through the treatment.
A
Being shoved from behind rarely causes whiplash.
The conclusion doesn’t say that people should get whiplash treatment after being shoved from behind.
B
Auto accidents often involve falling or being bumped on the head.
This doesn’t suggest that the whiplash treatment isn’t appropriate for every fall or bump on the head.
C
Nonautomobile accidents other than those involving falls or bumps on the head also occasionally cause whiplash injuries.
This doesn’t suggest that the whiplash treatment isn’t appropriate for every fall or bump on the head.
D
It is very uncommon for falling or being bumped on the head to result in a sudden sharp motion of the neck.
This calls into question the assumption that every fall or bump on the head involves a sudden, sharp movement in the neck. This shows we might not need whiplash treatment for some falls or bumps on the head.
E
The appropriate treatment for whiplash caused by a fall or a bump on the head is no different from that for whiplash caused by an auto accident.
The author never suggested that we need a different treatment for auto accidents. The author’s position is just that we should get whiplash treatment (regardless of whether it’s the same as that for auto accidents) for all falls and bumps on the head.